What is CVE-2026-59887?

CVE-2026-59887 is a high-severity vulnerability in Markdown-It Linkify-It, classified under Inefficient Algorithmic Complexity. CVSS score: 7.5/10. Published 2026-07-08.

How severe is CVE-2026-59887?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Markdown-It Linkify-It

CVE-2026-59887

linkify-it is a links recognition library with full Unicode support. Prior to 5.0.2, the mailto: schema validator used by .test() and .match() can be invoked at every mailto: occurrence and scan the remaining input through src_email_name in lib/re.mjs, causing O(n^2) CPU consumption on crafted user text. This issue is fixed in version 5.0.2.

EPSS: 0.003 (27.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Markdown-it Linkify-it — versions < 5.0.2

Weakness classification (CWE)

CWE-407 — Inefficient Algorithmic Complexity

References

security-advisories@github.com (x_refsource_CONFIRM)
security-advisories@github.com (x_refsource_MISC)
security-advisories@github.com (x_refsource_MISC)

Frequently asked questions

What is CVE-2026-59887?: CVE-2026-59887 is a high-severity vulnerability in Markdown-It Linkify-It, classified under Inefficient Algorithmic Complexity. CVSS score: 7.5/10. Published 2026-07-08.
How severe is CVE-2026-59887?: High severity. CVSS v3 base score is 7.5 out of 10.